The regulators of G protein signaling (RGS) proteins are important modulators of receptor and G protein signaling in cells. The long-term goal of this research is to understand the cellular roles for and regulation of RGS proteins in cell &organ patho/physiology. Our previous studies indicate that RGS14 is a highly unusual, multifunctional signaling protein that binds active Gi/oa subunits, inactive Gia subunits and Rap2, a Ras-like GTPase. Recently, we have discovered that RGS14 also binds, Ric8A, a non-receptor activator of Gia1, and H-Ras and Raf kinases. We hypothesize that RGS14 is a novel mediator of unconventional G protein signaling, but how RGS14 binds these proteins and regulates their activity is not known. When bound to its partners at the plasma membrane, RGS14 is phosphorylated with unknown functional consequences. We also have found that RGS14 is highly enriched in hippocampal neurons of the brain along with its binding partners Gia1, Rap2 and H-Ras, and other recent work shows that Gia1, H-Ras and Rap2 regulate important changes in hippocampal neurons relating to the "synaptic plasticity" that underlies learning and memory. To study RGS14 functions further, we have generated mice that lack the RGS14 gene (RGS14(-/-) or R14-KO) and found that these mice exhibit markedly enhanced learning and memory. My working hypothesis is that RGS14 is a tightly regulated switch/scaffolding protein that integrates unconventional G protein and Ras/Rap2/Raf signaling pathways to modulate specialized neuronal functions important for learning and memory. The Specific Aims will be to: Aim 1. Determine how RGS14 interacts with its binding partners to act as a signaling scaffold to mediate Ric8A and unconventional Gia and H-Ras, Rap2 and Raf kinase signaling. Aim 2: Determine sites on RGS14 that incorporate phosphate when complexed with Gia1/3, H-Ras or Rap2, and how phosphorylation impacts RGS14 signaling functions. Aim 3. Determine the effects of eliminating RGS14 gene/protein and its functions on cell morphology and known Gi and Ras/Rap2/Raf signaling events in hippocampal slices/neurons. Aim 4: Determine the effects of eliminating the RGS14 gene/protein on neuro- transmission (LTP, LTD) in hippocampal slices, and on hippocampal learning behaviors in mice. Impact: These studies will provide key insight about RGS14 as a novel integrator of neurotransmitter signaling events that modulate neuronal plasticity, learning and memory.